Mixing and spreading of different liquids are omnipresent in nature, life and technology, such as oil pollution on the sea1,2, estuaries3, food processing4, cosmetic and beverage industries5,6, lab-on-a-chip devices7, and polymer processing8. However, the mixing and spreading mechanisms for miscible liquids remain poorly characterized. Here, we show that a fully soluble liquid drop deposited on a liquid surface remains as a static lens without immediately spreading and mixing, and simultaneously a Marangoni-driven convective flow is generated, which are counterintuitive results when two liquids have different surface tensions. To understand the dynamics, we develop a theoretical model to predict the finite spreading time and length scales, the Marangoni-driven convection flow speed, and the finite timescale to establish the quasi-steady state for the Marangoni flow. The fundamental understanding of this solutal Marangoni flow may enable driving bulk flows and constructing an effective drug delivery and surface cleaning approach without causing surface contamination by immiscible chemical species.
People with contamination OCD may also experience fears of emotional contamination. For example, a person may fear that thinking or speaking about an illness will contaminate them. They may avoid talking about someone they know is sick because they are afraid any mention of this person will contaminate others. They might fear watching a movie or reading a book about someone ill will make them sick. 2b1af7f3a8